Bolt

ABSTRACT

A bolt, for use with curved pieces having aligned apertures, including ribs of trapezoidal cross section on the underside of the bolt head for engaging a portion of one of the apertures to prevent rotation of the bolt while tightening a nut thereon.

United States Patent Brown 1 Feb. 8, 11972 [54] BOLT FOREIGN PATENTS ORAPPLICATIONS [72] Inventor: Edward L. Brown, Middletown, Ohio 146,2344/1952 Australia ..151/41.5

. I 255,217 2/1963 Australia.... ....151/37 [73] Ass'gnee' 8:5 Mddlemwn666,534 3/1965 Belgium ..s5/9

533,732 12/1921 France ..l51/37 [22] Filed: Oct. 17, 1969 1,249,25411/1960 France ..15l/37 211 App]. No.2 867,274

[52] US. Cl ..l5l/37, 85/9 [51] Int. Cl ..Fl6b 39/282 [58] FieldofSearch..l5l/35,37,41.5; 85/9 [56] References Cited UNITED STATES PATENTS3,512,446 5/1970 Sekhon ..85/9

Primary Examiner-Marion Parsons, .lr. AttorneyMelville, Strasser, Foster& Hoffman 5 7] ABSTRACT A bolt, for use with curved pieces havingaligned apertures, including ribs of trapezoidal cross section on theunderside of the bolt head for engaging a portion of one of theapertures to prevent rotation of the bolt while tightening a nutthereon.

4 Claims, 5 Drawing Figum PATENTED FEB 8 I972 EDWARD L. BROWN BOLTBACKGROUND OF THE INVENTION This invention relates to a bolt headdesign, and has great and particular utility in the joining of steelpieces having aligned apertures formed in mating, curved surfaces.

Locking bolts of various descriptions are of course very old in the artand well known. The so-called carriage bolt for example, is providedwith a square shank portion immediately beneath the head, which squareshank portion is driven into one of two pieces to be joined to preventrotation of the bolt while the nut is tightened thereon.

Other locking bolt designs are shown in US. Pat. No. 1,857,388 in thename of Linderman et al., US. Pat. No. 2,562,032 in the name ofGutensohn, and US. Pat. No. 3,255,797 in the name of Attwood. All ofthese patents may be characterized as teaching a construction wherein aplurality of teeth are provided on the undersurface of the bolt head,which teeth, during the tightening operation engage the outer surface ofone of the members being bolted together and prevent rotation of thebolt during tightening.

It will readily be observed that in each of these cases, the ribs orteeth on the underside of the bolt head are sharply pointed tofacilitate the cutting or penetration of these teeth into the surface ofone of the members being joined.

The structure of these references is indeed effective to preventrotation of the bolt when tightening a nut thereon, when the bolt isused with a material into which the teeth or ribs can embed. When thematerial being bolted together is steel or the like, the problem issomewhat different. Although the bolt might be effective, with sharp,triangular teeth, the necessary degree of sharpness cannot be achievedin the conventional hot forging or cold heading operations.

SUMMARY OF THE INVENTION This invention, in its broadest aspect,contemplates a bolt for fastening together curved steel elements havingaligned apertures. The underside of the bolt head is provided with aplurality of radial ribs or teeth which are trapezoidal in crosssection, and arranged to engage a portion of one of the apertures insuch a manner as to prevent rotation of the bolt while tightening a nutthereon.

DESCRIPTION OF THE DRAWING FIG. 1 is a side elevational view of a boltaccording to this invention.

FIG. 2 is a cross-sectional view taken along the line 2-2 of FIG. 1.

FIG. 3 is a partial cross-sectional view taken along the line 3-3 ofFIG. 2.

FIG. 4 is a side elevational view similar to FIG. 1 showing amodification of the bolt according to this invention.

FIG. 5 is a crosssectional view taken along the line 5-5 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT As briefly indicated, the boltof this invention is particularly adapted for joining steel pieces wherethe bolt holes are punched in a curved surface such as a corrugation.Corrugated steel sheets have many applications both as generally flatsheets and in structures where the corrugated sheets are curved. Forexample, a product sold by Armco Steel Corporation under the trademarkMULTI-PLATE comprises a plurality of corrugated, curved steel pieces,adapted to be bolted together to form a tunnel, pipe arch, culvert, orthe like. Individual pieces of MULTI-PLATE are provided with aperturesalong all four edges, so that a completed structure is produced byoverlapping adjacent edges with apertures aligned, and bolting thepieces together.

Ordinarily, two men are utilized to insert the bolt and run the nut upfinger tight. When the structure is fully erected, all boltsmust then betightened. Instead of using two men, it is desirable to utilize a boltwhich will not turn as the nut is tightened, so that a single workmancan tighten all of the nuts from the same side of the structure.

Asjust indicated, the elements under consideration are corrugated andcurved. The aligned apertures for joining adjacent sections together,will be in both the hills and valleys of the corrugations. Under thesecircumstances. a conventional bolt having a substantially flat surfaceon the underside of the head has been found unsatisfactory, and the arthas developed a bolt having a flat head, but having the underside of thehead curved to a spherical radius substantially equal to the radius ofthe corrugations of the product in question. Such a bolt providesmaximum clamping action when utilized in the valleys of thecorrugations, and still performs very satisfactorily at the crest of thecorrugations.

The bolt of this invention shown in FIG. 1 comprises essentially amodification of the bolt just described. The bolt in-- cludes a threadedshank portion 10 which will be sized as desired, and which is entirelyconventional. The head of the bolt indicated generally in the drawingsat 12 is hexagonal in cross section and provided with the flat uppersurface 14. It will of course be understood that other cross-sectionalconfigurations may be utilized, and that if desired, the upper surfaceof the head of the bolt may be concave or convex as desired.

In the embodiment illustrated, it will be observed that the underside 16of the bolt heat 12 is shown as curved to a spheri cal radiussubstantially equal to the radius of the curved elements with which thebolt is to be used. However, since the ribs 18 (to be describedpresently) are the first points of contact with the edges of theaperture in the plates, it is only necessary that the rib outer contourbe generally spherical. The undersurface of the bolt head may be conicalso long as the ribs are adequately supported to resist undue formation.

As clearly shown in the drawings, the underside of the bolt head isprovided with the equally spaced ribs or teeth 18. in the embodimentshown in FIGS. 1-3, it will be observed that four equally spaced ribs 18are provided.

Referring now to FIG. 3, it will be seen that the ribs I8 aretrapezoidal in cross section. The sides 20 and 22 of the rib converge atan angle of approximately 20.

Referring to FIG. 1, it will be seen that the height of the rib l8gradually decreases radially outward from the bolt shank. While this isnot a requirement, the radius of curvature of the rig outer surfaceshould be equal to or less than the radius of curvature of thecorrugations. The ribs in the embodiment of FIG. 1 terminate short ofthe periphery of the bolt head which tends to minimize visibledisturbance of the plates being fastened. In order to insure engagementof the ribs with the edge of the bolt hole, the radial length of the ribshould be at least equal the designed clearance between bolt diameterand hole diameter.

It has been indicated throughout this specification that the bolt ofthis invention is intended primarily for use with a curved steelelement. It is recognized that when a perfectly round hole is formed ina curved element, the edges of the hole or aperture will not lie in asingle plane. Thus, when the bolt of this invention is inserted throughsuch an aperture, the bolt may be rotated so that four of the ribs arein contact with the edge of the aperture.

A full circumference of the aperture might be considered as having twohigh points or crests with two intermediate low points or valleys. Thus,the only position wherein four of the rigs 18 are in contact with theedge of the aperture is when each of the four ribs is intermediate oneof the high points and one of the low points. With reference to therotation of the bolt, it should thus be apparent that two diametricallyopposed ribs will be in contact with an upwardly sloping portion of theedge of the aperture, while the other two ribs will be in contact with adownwardly sloping portion of the edge of the aperture.

Since the top surface of the trapezoidal rib is tangent to the sphericalsurface defined by the ribs, it should be apparent that it will be thecorner of the trapezoidal rib 18 which will contact the upwardly slopingportion of the edge of the aperture as described above. Thus, a nearlyright-angle corner is presented to the edge of the aperture which cansecurely engage this edge portion of the aperture and prevent rotationof the bolt when a nut is being tightened thereon.

Surprisingly, it has been found that a sharper radius can be formed atthe edge of a trapezoid than at the ridge of a triangular shaped rib.Thus, the edge will grip the hole more securely and the mass of thetrapezoidal section will resist deformation better than a ridge on atriangular section.

As previously indicated, the height of the rib 18 decreases as the ribprogresses radially outward from the bolt stern. This constructionprovides for greater interference at the edge of the aperture, while atthe same time, providing less deformation of the piece away from theedge of the aperture.

A modification of the invention is shown in FIGS. 4 and 5. (Similarreference numerals have been used to identify corresponding parts in thetwo modifications.)

According to this modification, the ribs 18' extend all the way from theshank 10 of the bolt to the periphery of the head 12. This particulardesign permits certain economies in the manufacturing operation, and thenecessary forming dies are less expensive and have a somewhat longerlife.

In all other respects, the design of the bolt of this modification isidentical with the modification described earlier.

It is believed that the foregoing constitutes a full and completedisclosure of this invention, and no limitations are intended except asspecifically set forth in the claims which follow.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A bolt for use in structures comprising overlapping sections havingmating apertures in curved portions thereof, comprising a. a shank forpassage through said apertures having a threaded portion to receive anut b. a head on one end of said shank having on its underside aplurality of ribs of trapezoidal cross section with an arcuate outeraxial facing surface, said ribs extending from said shank radiallyoutward and decreasing in height and width from said shank radiallyoutwardly so as to define a continuously decreasing cross-sectionalarea, the figure of revolution defined by the outer surface of said ribsbeing a segment of a sphere the radius of which is not greater than thatof said curved portions, for engaging the edge of said apertures toprevent rotation of the bolt as a nut is tightened thereon.

2. The bolt claimed in claim 1 wherein said plurality of ribs comprisefour equally spaced ribs.

3. The bolt claimed in claim 1 wherein said ribs terminate short of theperiphery of said head.

4. The bolt claimed in claim 1 wherein the included angle of the sidesof said trapezoidal ribs equal substantially 20.

1. A bolt for use in structures comprising overlapping sections havingmating apertures in curved portions thereof, comprising a. a shank forpassage through said apertures having a threaded portion to receive anut b. a head on one end of said shank having on its underside aplurality of ribs of trapezoidal cross section with an arcuate outeraxial facing surface, said ribs extending from said shank radiallyoutward and decreasing in height and width from said shank radiallyoutwardly so as to define a continuously decreasing cross-sectionalarea, the figure of revolution defined by the outer surface of said ribsbeing a segment of a sphere the radius of which is not greater than thatof said curved portions, for engaging the edge of said apertures toprevent rotation of the bolt as a nut is tightened thereon.
 2. The boltclaimed in claim 1 wherein said plurality of ribs comprise four equallyspaced ribs.
 3. The bolt claimed in claim 1 wherein said ribs terminateshort of the periphery of said head.
 4. The bolt claimed in claim 1wherein the included angle of the sides of said trapezoidal ribs equalsubstantially 20* .